Integrated circuits are formed on semiconductor substrates, or wafers. The wafers are then sawed into microelectronic dies (or “dice”), or semiconductor chips, with each die carrying a respective integrated circuit. Each semiconductor chip is mounted to a package, or carrier substrate, which is often mounted to a motherboard and installed in various electronic systems.
In power integrated circuits, several semiconductor devices with voltage handling capability ranging from low to very high are integrated together. The devices with different characteristics and performance ratings need to be isolated from each other in order to prevent any cross-talk leading to malfunction in circuit operation. Thus, device-to-device isolation voltage capability, or “breakdown voltage,” is an important parameter in power integrated circuits. Traditional power integrated circuit technologies have commonly utilized a junction based isolation scheme which can give a desired isolation voltage, however, at the cost of increased device size.
One of the methods that has been attempted to improve breakdown voltage involves the formation of isolation trenches between the individual semiconductor devices (e.g., transistors). A single, floating conductor has been formed within the isolation trenches and surrounded by an insulating material, such as silicon dioxide. However, in such a configuration, if the voltage requirement is high, the thickness of the oxide around the conductor often becomes too great which, because of the differences in the coefficients of thermal expansion of the oxide and silicon, leads to severe mechanical stresses within the trenches and on the devices themselves. Such stresses can adversely affect the reliability of the devices.
Accordingly, it is desirable to provide a microelectronic assembly with an improved breakdown voltage between individual semiconductor devices. In addition, it is desirable to reduce the mechanical stresses experienced by the semiconductor devices. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.